1. Technical Field
The present invention relates to a virtual computer system including a plurality of virtual computers, and in particular to management of memory areas that are necessary for the virtual computers to operate.
2. Background Art
There is conventionally known a system in which hardware resources are multiplexed to improve the reliability of the system (for example, Patent Literature 1).
However, in the above method, the cost for multiplexing the hardware resources is too high. In view of this, some technologies use a plurality of virtual computers to improve the reliability of the system (for example, Patent Literatures 2 through 4).
Patent Literature 2 discloses a technology for obtaining, in advance, a backup of a memory area assigned to a virtual computer, and resuming a process by restoring the backup if an abnormality such as a hardware failure or a software malfunction occurs.
Patent Literature 3 discloses a technology for, if an abnormality occurs in one of two virtual computers that are run concurrently, causing the other one of the virtual computers to continue processing.
Patent Literature 4 discloses a technology for copying the content of a memory area assigned to a current-use virtual computer to a memory area assigned to a waiting virtual computer, and if an abnormality occurs in the current-use virtual computer, causing the processing to continue by switching from the current-use virtual computer to the waiting virtual computer.
Note that, to switch between a plurality of virtual computers, in general, a software called a hypervisor is used to manage the assignment of a processor, memory and the like to the virtual computers. A general role of the hypervisor has conventionally been known (for example, Patent Literature 5), and thus detailed description thereof is omitted here.